Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Experimentally induced antipredator responses are mediated by social and environmental factors
Groenewoud, Frank ; Kingma, Sjouke A. ; Bebbington, Kat ; Richardson, David S. ; Komdeur, Jan - \ 2019
Behavioral Ecology 30 (2019)4. - ISSN 1045-2249 - p. 986 - 992.
Antipredator defense - Nest defense - Nest predation - Parental investment - Seychelles warbler - Trade-off

Nest predation is a common cause of reproductive failure for many bird species, and various antipredator defense behaviors have evolved to reduce the risk of nest predation. However, trade-offs between current reproductive duties and future reproduction often limit the parent’s ability to respond to nest predation risk. Individual responses to experimentally increased nest predation risk can give insights into these trade-offs. Here, we investigate whether social and ecological factors affect individual responses to predation risk by experimentally manipulating the risk of nest predation using taxidermic mounts in the cooperative breeding Seychelles warbler (Acrocephalus sechellensis). Our results show that dominant females, but not males, alarm called more often when they confront a nest predator model alone than when they do so with a partner, and that individuals that confront a predator together attacked more than those that did so alone. Dominant males increased their antipredator defense by spending more time nest guarding after a presentation with a nest predator, compared with a nonpredator control, but no such effect was found for females, who did not increase the time spent incubating. In contrast to incubation by females, nest guarding responses by dominant males depended on the presence of other group members and food availability. These results suggest that while female investment in incubation is always high and not dependent on social and ecological conditions, males have a lower initial investment, which allows them to respond to sudden changes in nest predation risk.

Breeders that receive help age more slowly in a cooperatively breeding bird
Hammers, Martijn ; Kingma, Sjouke A. ; Spurgin, Lewis G. ; Bebbington, Kat ; Dugdale, Hannah L. ; Burke, Terry ; Komdeur, Jan ; Richardson, David S. - \ 2019
Nature Communications 10 (2019)1. - ISSN 2041-1723

Helping by group members is predicted to lead to delayed senescence by affecting the trade-off between current reproduction and future survival for dominant breeders. Here we investigate this prediction in the Seychelles warbler, Acrocephalus sechellensis, in which mainly female subordinate helpers (both co-breeders and non-breeding helpers) often help dominants raise offspring. We find that the late-life decline in survival usually observed in this species is greatly reduced in female dominants when a helper is present. Female dominants with a female helper show reduced telomere attrition, a measure that reflects biological ageing in this and other species. Finally, the probability of having female, but not male, helpers increases with dominant female age. Our results suggest that delayed senescence is a key benefit of cooperative breeding for elderly dominants and support the idea that sociality and delayed senescence are positively self-reinforcing. Such an effect may help explain why social species often have longer lifespans.

Compensatory and additive helper effects in the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis)
Boheemen, Lotte A. van; Hammers, Martijn ; Kingma, Sjouke A. ; Richardson, David S. ; Burke, Terry ; Komdeur, Jan ; Dugdale, Hannah L. - \ 2019
Ecology and Evolution 9 (2019)5. - ISSN 2045-7758 - p. 2986 - 2995.
additive care - compensatory care - cooperative breeding - investment strategies - load-lightening - parental care - Seychelles warbler

In cooperatively breeding species, care provided by helpers may affect the dominant breeders’ investment trade-offs between current and future reproduction. By negatively compensating for such additional care, breeders can reduce costs of reproduction and improve their own chances of survival. Alternatively, helper care can be additive to that of dominants, increasing the fledging fitness of the current brood. However, the influence helpers have on brood care may be affected by group size and territory quality. Therefore, the impact of helping needs to be disentangled from other factors determining offspring investment before conclusive inferences about the effect of help on additive and compensatory care can be made. We used 20 years of provisioning data to investigate the effect of helping on provisioning rates in the facultative cooperatively breeding Seychelles warbler Acrocephalus sechellensis. Our extensive dataset allowed us to statistically disentangle the effects of helper presence, living in larger groups and different food availability. We show compensatory and additive care (i.e., partial compensation) in response to helper provisioning. Helpers lightened the provisioning load of the dominant male and female and increased total provisioning to nestlings. This was irrespective of group size or territory quality (food availability). Moreover, our results illustrate sex-specific variation in parental care over the course of the breeding event. We discriminate between temporal variation, group size, and territory quality processes affecting cooperative care and as such, gain further insight into the importance of these factors to the evolutionary maintenance of helping behavior.

Stress behaviour and physiology of developing Arctic barnacle goslings (Branta leucopsis) is affected by legacy trace contaminants
Scheiber, Isabella B.R. ; Weiß, Brigitte M. ; Jong, Margje E. De; Braun, Anna ; Brink, Nico W. Van Den; Loonen, Maarten J.J.E. ; Millesi, Eva ; Komdeur, Jan - \ 2018
Proceedings of the Royal Society. B: Biological Sciences 285 (2018)1893. - ISSN 0962-8452
acute stress behaviour - Arctic - barnacle goose (Branta leucopsis) - HPA corticosterone metabolites - legacy trace metal contamination - stress coping

Natural populations are persistently exposed to environmental pollution, which may adversely impact animal physiology and behaviour and even compromise survival. Responding appropriately to any stressor ultimately might tip the scales for survival, as mistimed behaviour and inadequate physiological responses may be detrimental. Yet effects of legacy contamination on immediate physiological and behavioural stress coping abilities during acute stress are virtually unknown. Here, we assessed these effects in barnacle goslings (Branta leucopsis) at a historical coal mine site in the Arctic. For three weeks we led human-imprinted goslings, collected from nests in unpolluted areas, to feed in an abandoned coal mining area, where they were exposed to trace metals. As control we led their siblings to feed on clean grounds. After submitting both groups to three well-established stress tests (group isolation, individual isolation, on-back restraint), control goslings behaved calmer and excreted lower levels of corticosterone metabolites. Thus, legacy contamination may decisively change stress physiology and behaviour in long-lived vertebrates exposed at a young age.

Mercury associated neurochemical response in Arctic barnacle goslings (Branta leucopsis)
Brink, Nico W. van den; Scheiber, Isabella B.R. ; Jong, Margje E. de; Braun, Anna ; Arini, Adeline ; Basu, Niladri ; Berg, Hans van den; Komdeur, Jan ; Loonen, Maarten J.J.E. - \ 2018
Science of the Total Environment 624 (2018). - ISSN 0048-9697 - p. 1052 - 1058.
Exposure and effect - Neurotoxicity - Polar - Terrestrial - Tundra
There remains great concern over mercury pollution in the Arctic, though relatively little is known about impacts on biota that inhabit Arctic terrestrial systems. To help address this, the current study was performed with barnacle goslings (Branta leucopsis) from a coal mine-impacted site and a control site near Ny-Ålesund, Spitsbergen (Svalbard). The works focused mainly on mercury, as coal contains trace levels of this element. Total mercury concentrations were quantified in soil and vegetation from the two sites, as well as feces and liver from the goslings. Next, the mercury exposures were related to dopamine 2 (D2)- and NMDA-receptors in the brain, given that mercury is a proven neurotoxicant. Soil and vegetation in the mining area contained mercury levels that were approximately 3- and 2.2-times higher than in the control site. Despite a significant difference between the sites, the soil and vegetation mercury levels where were within ranges found at other Arctic locations. Goslings grazing in the mine-impacted area contained significantly higher hepatic mercury levels than those sampled from the control site. Compared to other species, the hepatic concentrations were relatively low possibly due to dilution of the mercury in growing goslings (growth dilution) and deposition of mercury in the growing feathers. Hepatic mercury concentrations were positively related to D2-neuroreceptor levels but not to NMDA-receptor levels thus suggesting a possible subtle neurological effect. To our knowledge, this is among the first studies on mercury exposure in Arctic terrestrial organisms, and one of the first to document potential subtle neurological responses associated with exposure to low, environmentally relevant mercury levels, which also can be found at other locations in the Arctic. However, as a pilot effort, the results here need to be examined in additional studies that include, for example, lager study designs, different geographic sites and other terrestrial species.
Indices of stress and immune function in Arctic barnacle goslings (Branta leucopsis) were impacted by social isolation but not a contaminated grazing environment
Jong, Margje E. de; Scheiber, Isabella B.R. ; Brink, Nico W. van den; Braun, Anna ; Matson, Kevin D. ; Komdeur, Jan ; Loonen, Maarten J.J.E. - \ 2017
Science of the Total Environment 601-602 (2017). - ISSN 0048-9697 - p. 132 - 141.
Acute phase proteins - Complement - Corticosterone - Heavy metals - Natural antibodies - Nitric oxide

In many areas around the Arctic remains and spoil heaps of old mines can be found, which have been abandoned after their heydays. Runoff from tailings of these abandoned mines can directly contaminate the local environment with elevated concentrations of trace metals. Few studies have investigated the possible negative effects of contaminants on Arctic terrestrial animals that use these areas. Trace metals can accumulate in animals and this accumulation has been linked to negative effects on fitness. Both, the hypothalamus-pituitary-adrenal (HPA) axis and/or the immune system have been named as possible underlying causes for these observations. Free-living animals are often exposed to multiple stressors simultaneously, however, and this is often not considered in studies on the effects of contaminants on animal physiology. Here, we performed a study on Spitsbergen (Svalbard) taking both potential effects of trace metal contamination and social stress into account. We investigated experimentally effects of exposure to contaminants from a historic coal mine area on plasma corticosterone levels and on four innate immune parameters (haemolysis, haemagglutination, haptoglobin-like activity and nitric oxide) before and after social isolation in human-raised barnacle goslings (Branta leucopsis). Baseline corticosterone and immune parameters were not affected by mine-exposure. After social isolation, mine goslings tended to show decreased haemagglutination in comparison with control goslings, but we detected no difference in the other measures. Social isolation increased corticosterone and decreased haptoglobin-like activity in all goslings. Immunology and corticosterone levels of barnacle goslings thus seem unaffected, at least on the short term, by Arctic coal mining contamination.

Low but contrasting neutral genetic differentiation shaped by winter temperature in European great tits
Lemoine, Mélissa ; Lucek, Kay ; Perrier, Charles ; Saladin, Verena ; Adriaensen, Frank ; Barba, Emilio ; Belda, Eduardo J. ; Charmantier, Anne ; Cichoń, Mariusz ; Eeva, Tapio ; Grégoire, Arnaud ; Hinde, Camilla A. ; Johnsen, Arild ; Komdeur, Jan ; Mänd, Raivo ; Matthysen, Erik ; Norte, Ana Cláudia ; Pitala, Natalia ; Sheldon, Ben C. ; Slagsvold, Tore ; Tinbergen, Joost M. ; Török, János ; Ubels, Richard ; Oers, Kees van; Visser, Marcel E. ; Doligez, Blandine ; Richner, Heinz - \ 2016
Biological Journal of the Linnean Society (2016). - ISSN 0024-4066 - p. 668 - 685.
F-statistics - Isolation-by-distance - Latitude - Microsatellites - Parus major - Population genetic structure - Winter severity

Gene flow is usually thought to reduce genetic divergence and impede local adaptation by homogenising gene pools between populations. However, evidence for local adaptation and phenotypic differentiation in highly mobile species, experiencing high levels of gene flow, is emerging. Assessing population genetic structure at different spatial scales is thus a crucial step towards understanding mechanisms underlying intraspecific differentiation and diversification. Here, we studied the population genetic structure of a highly mobile species - the great tit Parus major - at different spatial scales. We analysed 884 individuals from 30 sites across Europe including 10 close-by sites (<50 km), using 22 microsatellite markers. Overall we found a low but significant genetic differentiation among sites (FST = 0.008). Genetic differentiation was higher, and genetic diversity lower, in south-western Europe. These regional differences were statistically best explained by winter temperature. Overall, our results suggest that great tits form a single patchy metapopulation across Europe, in which genetic differentiation is independent of geographical distance and gene flow may be regulated by environmental factors via movements related to winter severity. This might have important implications for the evolutionary trajectories of sub-populations, especially in the context of climate change, and calls for future investigations of local differences in costs and benefits of philopatry at large scales.

Response to habitat modification by foraging Dark-chanting Goshawks Melierax metabates in a West African savanna
Buij, Ralph ; Dorst, Nikie Van; Salomons, Henriëtte F. ; Croes, Barbara M. ; Dietz, Maurine W. ; Komdeur, Jan - \ 2015
Bird Conservation International 25 (2015)3. - ISSN 0959-2709 - p. 335 - 352.

Anthropogenic habitat alteration has probably contributed significantly to the decrease of raptor populations in West African savannas. To evaluate the impact of habitat degradation on foraging by sedentary Afrotropical raptors, we investigated the differences in microhabitat selection, foraging effort and energy returns between Dark-chanting Goshawks Melierax metabates inhabiting natural and transformed savannas in Cameroon. We expected that the agro-ecosystems in the transformed savannas have become unprofitable for Dark-chanting Goshawks due to scarcity of food resources. In both savanna types we radio-tracked six mated, adult males during the non-breeding season and determined foraging effort, by time spent at each perch and distance covered between perches, and energy intake through estimation of the energy value of prey items. Goshawks in natural habitats had smaller home-ranges and exploited their range more intensively than Goshawks in transformed habitats. In both natural and transformed habitats, Goshawks selected foraging patches with comparatively tall trees, underlining their importance to foraging Goshawks. The extent of shrub and herbaceous layer cover, agriculture cover, and tree density were other important predictors of foraging patch use, but their importance differed between habitats. The extent of shrub, herbaceous layer and agriculture cover were positively associated with foraging patch use in transformed habitats, suggesting that cultivated fields and ground vegetation support important prey resources for Goshawks in agro-ecosystems. The composition of broad prey categories to the diet, foraging effort and returns were comparable between habitats. However, we found indications that the proportion of heavy-bodied lizard species among reptile prey items was higher in natural than transformed habitats, whereas on average smaller lizards were more commonly caught in the latter. Mean herbaceous layer height and tree density within home ranges, both higher in natural habitat, were negatively related to prey capture rates. Tree clearance and livestock grazing thus favored greater prey capture rates in transformed habitat, offsetting a lower meal energy value compared to natural habitat. We conclude that foraging Dark-chanting Goshawks may cope with moderate land transformation, but practices focused on conservation of tall trees and ground vegetation cover would be beneficial by maintaining important prey resources and their exploitability under growing land pressure.

Fewer invited talks by women in evolutionary biology sympsosia
Schroeder, J. ; Dugdale, H.L. ; Radersma, R. ; Hinsch, M. ; Buehler, D.M. ; Saul, J. ; Porter, L. ; Liker, A. ; Cauwer, I. de; Johnson, P.J. ; Santure, A.W. ; Griffin, A.S. ; Bolund, E. ; Ross, L. ; Webb, T.J. ; Feulner, P.G.D. ; Winney, I. ; Szulkin, M. ; Komdeur, J. ; Versteegh, M.A. ; Hemelrijk, C.K. ; Svensson, E.I. ; Edwards, H. ; Karlsson, M. ; West, S.A. ; Barrett, E.L.B. ; Richardson, D.S. ; Brink, V. van den; Wimpenny, J.H. ; Ellwood, S.A. ; Rees, M. van; Matson, K.D. - \ 2013
Journal of Evolutionary Biology 26 (2013)9. - ISSN 1010-061X - p. 2063 - 2069.
gender-differences - job applicants - science - recommendation - visibility - professors - female
Lower visibility of female scientists, compared to male scientists, is a potential reason for the under-representation of women among senior academic ranks. Visibility in the scientific community stems partly from presenting research as an invited speaker at organized meetings. We analysed the sex ratio of presenters at the European Society for Evolutionary Biology (ESEB) Congress 2011, where all abstract submissions were accepted for presentation. Women were under-represented among invited speakers at symposia (15% women) compared to all presenters (46%), regular oral presenters (41%) and plenary speakers (25%). At the ESEB congresses in 2001–2011, 9–23% of invited speakers were women. This under-representation of women is partly attributable to a larger proportion of women, than men, declining invitations: in 2011, 50% of women declined an invitation to speak compared to 26% of men. We expect invited speakers to be scientists from top ranked institutions or authors of recent papers in high-impact journals. Considering all invited speakers (including declined invitations), 23% were women. This was lower than the baseline sex ratios of early-mid career stage scientists, but was similar to senior scientists and authors that have published in high-impact journals. High-quality science by women therefore has low exposure at international meetings, which will constrain Evolutionary Biology from reaching its full potential. We wish to highlight the wider implications of turning down invitations to speak, and encourage conference organizers to implement steps to increase acceptance rates of invited talks.
Effects of land-use change and rainfall in Sudano-Sahelian West Africa on the diet and nestling growth rates of an avian predator
Buij, R. ; Folkertsma, I. ; Kortekaas, K. ; longh, H.H. De; Komdeur, J. - \ 2013
Ibis 155 (2013)1. - ISSN 0019-1019 - p. 89 - 101.
field energetics - breeding success - protected areas - hatching order - climate-change - foraging mode - national-park - raptors - habitat - savanna
Raptor populations in Sudano-Sahelian West Africa are being severely affected by widespread habitat alteration which depletes prey populations, potentially aggravated by changing rainfall patterns. We studied Grasshopper Buzzards Butastur rufipennis at nests in natural and transformed habitats in the Sudano-Sahelian region of northern Cameroon to assess the effects of habbitat transformation and rainfall on nestling diet and growth.
The role of breeding range, diet, mobility and body size in associations of raptor communities and land-use in a West African savannah
Buij, R. ; Croes, B.M. ; Gort, G. ; Komdeur, J. - \ 2013
Biological Conservation 166 (2013). - ISSN 0006-3207 - p. 231 - 246.
long-term assessment - protected areas - southern-africa - burkina-faso - conservation - habitat - declines - cameroon - biodiversity - population
To provide insight into raptor declines in western Africa, we investigated associations between land-use and raptor distribution patterns in Cameroon. We examined the role of breeding distribution, species’ migratory mobility, diet, body size, and thus area requirements, on 5-km scale patterns of raptor richness and abundance. We recorded 15,661 individuals, comprising 55 species during road surveys, spanning four annual cycles. Results revealed evidence for the importance of National Parks (N.P.’s), natural vegetation, humans, and cotton in shaping raptor assemblages, but responses differed between functional groups and biogeographical zones. Human populations and natural habitat, interacting with zone, were important predictors of Afrotropical raptor richness, and N.P.’s of Palearctic raptor richness. Areas cleared of natural habitat in the Guinea zone had comparatively rich and abundant large, small sedentary and migratory Afrotropical raptor assemblages, but humans limited positive effects. Palearctic raptor abundance peaked at higher levels of human land-use than Afrotropical raptors. Vertebrate-hunting Palearctic raptor richness was positively associated with cropland, while cotton and human land-use in the Inundation zone had a stronger negative impact on insectivorous Palearctic raptors. Richness of large sedentary raptors declined with increasing distance to N.P.’s, contrary to communal scavenger richness, which increased with human populations. Humans, habitat loss and cotton in the Inundation and Sudan zones had similar, negative effects on small sedentary and small migratory Afrotropical raptor assemblages. We conclude that increasing human populations, natural vegetation loss, and expanding cotton will negatively affect the majority of Afrotropical and insectivorous Palearctic raptors, while vertebrate-hunting Palearctic raptors may benefit from cropland expansion.
Breeding performance of the Grasshopper Buzzard (Butastur rufipennis) in a natural and a human-modified West African savanna
Buij, R. ; Kortekaas, K. ; Krimpen, R.R.D. ; Wijk, H.J. van; Zanden, S. ; Iongh, H.H. de; Heitkonig, I.M.A. ; Snoo, G.R. de; Komdeur, J. - \ 2013
Condor 115 (2013)1. - ISSN 0010-5422 - p. 47 - 57.
nest-site selection - owls asio-otus - land-use - climate-change - survival estimation - raptor community - protected areas - arid savanna - habitat - success
Few studies have examined raptor reproduction in response to land-use change in sub-Saharan Africa, hampering conservation efforts to address regional declines. To further our understanding of mechanisms underlying the dramatic declines of West African raptors, we examined the relationship between environmental conditions, nest density, and measures of reproduction in the Grasshopper Buzzard (Butastur rufipennis). Analyses were based on 244 nest sites divided between transformed and natural habitat in northern Cameroon. At the landscape scale, nest density increased with the density of preferred nest trees. Nests were more widely spaced in transformed than in natural habitat. Dispersion was adjusted to differences in availability of small mammals, which was negatively associated with distance to nearest neighbor, and in the area under cultivation, which was positively associated with distance to nearest neighbor. Productivity was positively associated with rainfall, canopy shielding the nest, availability of grasshoppers, and the nest's visibility from ground level; canopy shielding, grass cover, rainfall, and distance to nearest neighbor were positively associated with nest success. In natural habitat, losses of eggs and nestlings to natural predators were greater than in transformed habitats, while losses through human predation were small. Productivity and nest success were unaffected by land use because of the opposing effects of greater predation pressure, closer spacing of nests, and more food in natural habitat than in transformed habitat. Thus transformed habitat may provide adequate breeding habitat for the Grasshopper Buzzard, but declining rainfall and intensifying anthropogenic land use are likely to affect future reproductive output
Breeding biology and nestling development of the Grasshopper Buzzard
Buij, R. ; Kortekaas, K. ; Folkertsma, I. ; Velde, M. van der; Komdeur, J. ; Iongh, H.H. de - \ 2012
Ostrich 83 (2012)3. - ISSN 0030-6525 - p. 137 - 146.
prey-size hypothesis - kite milvus-migrans - sex-ratio - american kestrels - sibling aggression - brood reduction - parental investment - seasonal-variation - west-africa - growth
Research into the effect of environmental variables on reproductive success of tropical raptors is often constrained by the lack of information on breeding biology. We provide the first detailed information of the breeding biology and nestling development of the Grasshopper Buzzard Butastur rufipennis, an Afrotropical migratory raptor threatenend by extensive land transformation in its breeding range.
Interspecific and intraspecific differences in habitat use and their conservation implications for Palaearctic harriers on Sahelian wintering grounds
Buij, R. ; Goes, D. van der; Iongh, H.H. de; Gagare, S. ; Haccou, P. ; Komdeur, J. ; Snoo, G.R. de - \ 2012
Ibis 154 (2012)1. - ISSN 0019-1019 - p. 96 - 110.
field metabolic-rate - circus-aeruginosus - land-use - body-size - arvicanthis-niloticus - prey availability - northern harriers - breeding season - protected areas - survival rates
The floodplains of the West-African Shale region have experienced extensive habitat transformation during the past four decades, coinciding an impoverishment of raptor populations. We investigated foraging patterns of Palaearctic migratory Eurasian Marsh Harriers Circus aeruginosus, Pallid Harriers C. macrourus and Montagu's Harriers C. pygargus on a floodplain system in northem Cameroon to assess species, sex-and agerelated habitat preferences.
Laboratory tests for controlling poultry red mites (Dermanyssus gallinae) with predatory mites in small ‘laying hen’ cages
Lesna, I. ; Sabelis, M.W. ; Niekerk, T.G.C.M. van; Komdeur, J. - \ 2012
Experimental and Applied Acarology 58 (2012)4. - ISSN 0168-8162 - p. 371 - 383.
biological-control - acari - susceptibility - ectoparasites - mesostigmata - management - stand
To assess their potential to control poultry red mites (Dermanyssus gallinae), we tested selected predaceous mites (Androlaelaps casalis and Stratiolaelaps scimitus) that occur naturally in wild bird nests or sometimes spontaneously invade poultry houses. This was done under laboratory conditions in cages, each with 2–3 laying hens, initially 300 poultry red mites and later the release of 1,000 predators. These small-scale tests were designed to prevent mite escape from the cages and they were carried out in three replicates at each of three temperature regimes: 26, 30 (constant day and night) and 33–25 °C (day-night cycle). After 6 weeks total population sizes of poultry red mites and predatory mites were assessed. For the temperature regimes of 26 and 33/25 °C S. scimitus reduced the poultry red mite population relative to the control experiments by a factor 3 and 30, respectively, and A. casalis by a factor of 18 and 55, respectively. At 30 °C the predators had less effect on red mites, with a reduction of 1.3-fold for S. scimitus and 5.6-fold for A. casalis. This possibly reflected hen manure condition or an effect of other invertebrates in the hen feed. Poultry red mite control was not negatively affected by temperatures as high as 33 °C and was always better in trials with A. casalis than in those with S. scimitus. In none of the experiments predators managed to eradicate the population of poultry red mites. This may be due to a prey refuge effect since most predatory mites were found in and around the manure tray at the bottom of the cage, whereas most poultry red mites were found higher up in the cage (i.e. on the walls, the cover, the perch, the nest box and the food box). The efficacy of applying predatory mites in the poultry industry may be promoted by reducing this refuge effect, boosting predatory mite populations using alternative prey and prolonged predator release devices. Biocontrol success, however, will strongly depend on how the poultry is housed in practice (free range, cage or aviary systems) and on which chemicals are applied to disinfect poultry houses and to control other pests
Effects of immune supplementation and immune challenge on oxidative status and physiology in a model bird: implications for ecologists
Crommenacker, J. van de; Horrocks, N.P.C. ; Versteegh, M.A. ; Tieleman, B.I. ; Komdeur, J. ; Matson, K.D. - \ 2010
Journal of Experimental Biology 213 (2010)20. - ISSN 0022-0949 - p. 3527 - 3535.
history trade-offs - life-history - antioxidant protection - plasma carotenoids - oxygen-consumption - lysozyme turnover - barn swallow - great tits - stress - haptoglobin
One route to gain insight into the causes and consequences of ecological differentiation is to understand the underlying physiological mechanisms. We explored the relationships between immunological and oxidative status and investigated how birds cope physiologically with the effects of immune-derived oxidative damage. We successively implemented two experimental manipulations to alter physiological status in a model bird species: the homing pigeon (Columba livia). The first manipulation, an immune supplementation, was achieved by oral administration of lysozyme, a naturally occurring and non-specific antimicrobial enzyme. The second manipulation, an immune challenge, took the form of an injection with lipopolysaccharide, a bacterial endotoxin. Between groups of lysozyme-treated and control birds, we compared lipopolysaccharide-induced changes in reactive oxygen metabolites, total antioxidant capacity, haptoglobin, oxygen consumption, body mass and cloacal temperature. Lysozyme supplementation intensified the lipopolysaccharide-induced inflammatory response and generated short-term oxidative and metabolic costs. We identified significant interactions between immune supplementation and immune challenge in terms of reactive oxygen metabolites, haptoglobin and oxygen consumption. Our study provides alternative interpretations of differences in oxidative and immunological indices and demonstrates that these indices can also fluctuate and interact across very short time scales, reflecting something akin to current ‘health status’ or ‘physiological condition’. These ephemeral effects highlight the need to broadly consider current physiological condition when drawing conclusions that relate physiology to ecology and evolution.
Population size, breeding habitat and nest site distribution of little penguins (Eudyptula minor) on Montague Island, New South Wales
Weerheim, M.S. ; Klomp, N.I. ; Brunsting, A.M.H. ; Komdeur, J. - \ 2003
Wildlife Research 30 (2003)2. - ISSN 1035-3712 - p. 151 - 157.
The distribution of little penguin nest sites on Montague Island, New South Wales, was examined in relation to vegetation type, distance to landing sites and local footpaths. Nest site density was negatively correlated with distance to landing sites and positively correlated with distance to footpaths. The latter may be related to disturbance. Comparisons with the transect data of previous years showed a significant shift in nest distribution away from areas dominated by dense kikuyu grass. In October 2000, the little penguin population on Montague Island was estimated at 5000 breeding pairs. However, repeat surveys in November and December showed that single counts underestimate the actual size of the breeding population. This study has demonstrated the value of line transects to examine the relationship between little penguins and their breeding habitat. Transect surveys on Montague Island should continue in future years to monitor the effects of ongoing vegetation changes on nest distribution and population size.
De betekenis van dood hout voor avifauna
Komdeur, J. ; Vestjens, J.P.M. - \ 1983
Nederlands Bosbouwtijdschrift 55 (1983)2/3. - ISSN 0028-2057 - p. 86 - 90.
vogels - bosecologie - dood hout - birds - forest ecology - dead wood
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